The purpose of this research project is to examine the problems under international law concerning the prosecution and punishment of the leaders of Pol Pot regime who have the responsibilities for the genocide over 1.7 million people in Cambodia. The research is centered on the analysis of the long process of negotiations leading to the establishment of the hyper tribunal, which will be agreed upon between the United Nations and the Cambodian government in the last year, 2003.This report is consists of the following five chapters. The first chapter examines how and why the genocide occurred under the Khmer Rouge government. In the second chapter the author makes a negative assessment for the works of the people's trial against Pol Pot's crime under the Vietnamese influenced government in August 1979, and look back the period of confrontation between the two governments in the 1980's. The third chapter evaluates the status of the Paris peace agreement and the process of peace keeping operations under the UNTAC. The chapter four deals with the process of negotiations between the UN and Cambodian government concerning the establishment of the hybrid tribunal within the framework of the Cambodian domestic legal order. This is not the type of international tribunal as we see in the cases of the Former Yugoslavia or Rwanda, but is a mixed court that is composed of Cambodian and international judges, prosecutors and investigation judges. The chapter fiveThe author tries to point out the importance of the trial not only from the standpoint of the universal enforcement of international criminal law, but also for pursuing the reconstructive justice for the sake of the Cambodian people whose friends, families and relatives were the victims of this grave human tragedy. However the future success of this tribunal is not assured yet. There are lots of difficulties to be overcome.